Electric can opener

ABSTRACT

An electric can opener having a rotatable cutter which cuts through and around a seaming (outer) wall of a double seam (chime) by which a can is secured to a can body. The rotatable cutter and a tractor wheel turn about axes which are substantially perpendicular to each other. The tractor wheel can be axially shifted by manual movement of an operating lever. The tractor wheel has a conical surface disposed to engage a chuck (inner) wall of a chime and a cylindrical surface disposed to engage the top of a chime. Associated with the cutter is a shoulder wheel that rides on the outside of a can below the chime so that the can opener will hold a can after a seaming wall is cut entirely around a can and until a can is deliberately released by axially shifting the tractor wheel out of engagement with a chime. A first abutment above a chime and ahead of the tractor wheel (the direction of rotation of a can being the reference) extends forward from a can opener housing. Asecond forwardly extending abutment above a chime is located behind the tractor wheel.

United States Patent McLaren, Jr. et al.

ELECTRIC CAN OPENER Inventors: Vincent H. McLaren, Jr.,

Cumberland; Navnit Panchal, Riverside, both of R.1.

Assignee: Imperial Knife Associated Companies, Inc., New York, NY.

Filed: Dec. 29, 1972 Appl. No.: 319,302

1 Related US. Application Data Division of Ser. No. 192,400, Oct. 26,1971.

US. Cl 82/47, 82/48, 82/78,

82/92, 82/97 Int. Cl B671) 7/38, B23b 1/00 Field of Search 30/4 R, 15.5,9; 82/47,

"References Cited UNITED STATES PATENTS Posenerml 30/4 R PrimaryExaminer-Al Lawrence Smith Assistant ExaminerGary L. Smith Attorney,Agent, or FirmKirschstein, Kirschstein, Ot-

tinger & Frank 57 ABSTRACT An electric can opener having a rotatablecutter which cuts through and around a seaming (outer) wall of a doubleseam (chime) by which a can is secured to a can body. The rotatablecutter and a tractor wheel turn about axes which are substantiallyperpendicular to each other. The tractor wheel can be axially shifted bymanual movement of an operating lever. The tractor wheel has a conicalsurface disposed to engage a chuck (inner) wall of a chime and acylindrical surface disposed to engage the top of a chime. Associatedwith the cutter is a shoulder wheel that rides on the outside of a canbelow the chime so that the can opener will hold a can after a seamingwall is cut entirely around a can and until a can is deliberatelyreleased by axially shifting the tractor wheel out of engagement with a'chime. A first abutment above a chime and ahead of the tractor wheel(the direction of rotation of a can being the reference) extends forwardfrom a can opener housing. Asecond forwardly extending abutment above achime is located behind the tractor wheel.

1 C .e w. 5 B ew e,

iATENTEUHAY 71914 I 3Q808l917 sum 3 OF 6 PATENTEU HAY 1974 sum 6 OF 6 FIG.

FIG. /2

ELECTRIC CAN OPENER This is a division of application Ser. No. 192,400filed Oct. 26, 1971.

Prior to a can cutting operation the tractor wheel is axially shiftedfar enough from the cutter to freely admit a chime pressed against thecylindrical surface of the tractor wheel and the second abutment, thusorienting a chime at a proper angle for engagement by the cutter when,thereafter, the tractor wheel is axially shifted toward the cutter. Suchmovement of the-tractor wheel squeezes a chime between the cutter andthe tractor wheel and sinks the periphery of the cutter into a seamingwall.

The cutter is positioned with the plane of its cutting rim at an angleto the direction of cut around a chime. Hence, sinking the cutter into aseaming wall raises a small hump at the top of a chime. Also upondepression of the operating lever an electric motor is actuated to startrotation of the tractor wheel and consequent turning of a can withrespect to the cutter. As the can turns about the cutter the tiltedposition of the cutter swings the can about the axis of rotation of thetractor wheel, as explained in Fyfe-U.S.l. Pat. No. 3,510,941 issued May12, 1970, the tilting being in a direction such that the chime of thecan, while remaining in engagement with the driving tractor wheel,swings out of contact with the second abutment and into contact with thefirst abutment. In this position the top of the can is almosthorizontal. This swinging of the can increases the height of the hump.Continued operation of the motor causes the cutter wheel to cut aroundthe seaming wall of the chime behind the tractor wheel, the hump movingforwardly away from the tractor wheel as cutting progresses until thehump approaches the tractor wheel from behind at which time the humpreaches a sensor that rides on the top of the chime behind the tractorwheel. The hump lifts the sensor slightly before a 360 rotation of thecan or, in other words, just before the cut is completed. Lifting thesensor initiates the actuation of a mechanism for deactivating theoperation of the can opener electric motor. The deactivating mechanismincludes a tripping device for deenergizing the motor. The trippingdevice has a delay cycle which is commenced when the sensor reaches thehump. The delay cycle permits continuation of the cutting operation fora few additional degrees of rotation of the can beyond the point wherethe hump lifts the sensor. Thereupon, the motor is deenergized, with thecan opener stopping at or slightly beyond the end of a 360 rotation andthe cutting cycle is completed. The can is released from the can openerby raising theoperating lever to shift the tractor wheel away from thecutter.

BACKGROUND OF THE INVENTION 1. Field of the Invention An end-of-cutmotor shut off for an electric can opener having a rotatable cutterwhich cuts through a seaming wall of a double seam securing a can end toa can body.

2. Description of the Prior Art Conventional can openers cut a flat endwall ofa can inside of a chime. This tends to create undesirable metalslivers as the cutter shears an end wall and scrapes against a canchime. The metal slivers may bell into the opened can where they are asafety hazard.

With such a can opener that is electrically powered, completion of a cutis detected by sensing the large drop in torque that takes place upontermination of the cut. However, with an electric can opener utilizing acutter for a seaming wall, differential torque sensing of the completionof cut cannot be relied upon for deener gizing the can opener for thefollowing reason. When a chime of a can is cut by the latter type canopener, it is squeezed between the cutting wheel riding on a seamingwall of a chime and the tractor wheel riding on a chuck wall of a chime.The reduction in torque for a given can occurring at the completion of acut is relatively small compared, for example, to the difference inmotor torques required to cut through cans of different sizes or throughcans having different thicknesses of chimes. Differential motor torquesensing devices to detect the end of a cut in a can opener of this typeare, accordingly, not a reliable parameter for sensing the completion ofa cut.

SUMMARY OF THE INVENTION PURPOSES OF THE INVENTION It is an object ofthe present invention to provide a simple, economical electrical canopener which will cut through a can chime seaming wall and which can beused to open cans of the full range of diameters now used by the canningindustry and, further, which can be' employed by housewives having a lowdegree of manual dexterity and strength.

It is another object of this invention to provide an electriccan openerof thecharacter described whichcreates a hump at the top of a chime as acut is made in a seaming wall and also means for sensing the arrival ofthe hump near the completion of a cut and responsive to such sensinghalting the powered cuttingoperation.

It is another object of this invention to provide an end-of-cut sensorfor an electric can opener of the character described which is not adifferential torque sensing device and which insures a full 360 cut ofthe can.

It is a further object of this invention to provide a tripping mechanismwhich is operated responsive to the almost substantial completion of achime cutfor continuing the cut a few degrees to complete a 360 rotationof a can during cutting whereby to insure full separation of a can endfrom a can body.

It is another object of this invention to provide an electric can openerhaving a motor for driving the cutting wheel together with mechanicalsensing means for detecting the completion of a cut and for thereupondeenergizing the motor.

Further objects and features of this invention will become apparent uponconsideration of the following description when read in conjunction withthe drawings.

BRIEF DESCRIPTION OF THE INVENTION A can opener which cuts through aseaming wall of a chime by which a can end is secured to a can body. Thecan opener has a rotatable cutter and a tractor wheel. The tractor wheelhas a conical chuck wall engaging surface and also has a coaxialcylindrical surface parallel to the axis of the tractor wheel. Thecylindrical surface is disposed to engage the top of a chime. The cutterand the tractor wheel are rotatable about axes at right angles to oneanother. The can opener includes first and second abutments extendingforwardly from a face of a can opener housing about a chime. Theabutments are ahead of and behind the tractor wheel, respectivelyconsidered in the direction of movement of a can during a cuttingoperation.

Prior to a powered can cutting operation the tractor wheel is axiallyshifted far enough in front of the cutter to freely admit a chime withthe chime pressed against the cylindrical surface of the tractor wheeland against the second abutment whereby to orient the seaming wall at aproper angle for engagement by the cutter when the tractor wheel isaxially shifted toward the cutter upon depression of an operating lever;Rearward movement of the tractor wheel squeezes the chime between thecutter and the conical surface of the tractor wheel and sinks theperiphery of the cutter into the seaming wall. Engagement of the chimewith the tractor wheel and second abutment as aforesaid determines theangle of the top of the can with respect to the plane of the cutting rimof the cutter before a can opener motor is energized. Upon depression ofthe operating lever a can opener electric motor is actuated to startrotation of the tractor wheel and consequent turning of the can. As thecan starts to turn the cutter swings the can about the axis of rotationof the tractor wheel, causing the chime to move away from the secondabutment and into engagement with the first abutment while remaining inengagement with the tractor wheel, as explained in Fyfe, U. S. Pat. No.3,510,941, issued May 12, 1970.

The cutter wheel has associated with it a shoulder wheel that rides on aside of a can below a chime. Engagement of this shoulder wheel with theouter surface of a can holds the stationary can against the tractorwheel after the cutter wheel has completed its cut of the seaming walland until the can is deliberately released by axial outward displacementof the tractor wheel away from the housing upon lifting of the operatinglever.

As the cutter sinks into the seaming wall and as the can changes itsinclination in the manner aforesaid, a hump is raised on the top of thechime. This hump is used to determine when the cutting operation issubstantially complete, such determination being in lieu of thedifferential torque sensing means employed in conventional electricallypowered can openers. For this purpose the can opener includes a sensorwhich rides on the top of the chime behind the tractor wheel. The sensoris not actuated as the hump leaves the tractor wheel, but rathercontinues to ride at a constant elevation on the top edge of the chime.However, when the hump completes almost 360 of rotation and approachesthe tractor wheel, the hump lifts the sensor. When the sensor is liftedit actuates a tripping mechanism which initiates a delay cycle. Thistripping mechanism, after a few more degrees of rotation of the can pastthe cutter, shuts off the motor. The delay provided by the trippingmechanism permits the cutter to cut through the seaming wall up to andpast the hump-at the beginning of the cut so as to provide for completeseparation of the can end from the can body.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings in whichis shown one of the various possible embodiments of the invention:

of the invention illustrating the position of a can as it is approachedinto engagement with the idle can opener;

FIG. 2 is an exploded perspective view of the main components of theelectric can opener;

FIG. 3 is an enlarged fragmentary front view of the can opener andillustrates the position of a can upon engagement by'the cutter andtractor wheel at the instant that the cutter sinks into a seaming wall;

FIG. 4 is a sectional top view-taken substantially along the line 4-4 ofFIG. 3, the tractor wheel being shown in solid lines in its retractedposition adjacent the housing in which position of a chime of a can tobe cut is squeezed between the tractor wheel and the cutter, and thetractor wheel being illustrated in dot-anddash lines in its forwardlyextended position in which position a chime is adapted to be insertedbetween or withdrawn from the space between the tractor wheel and thecutter;

FIG. 5 is a vertical sectional view taken substantially along the line5-5 of FIG. 4 and illustrates the relationship between the tractor wheeland the cutter; in this figure, likewise, the tractor wheel is showninfull lines inits retracted position and in dot-and-dash linesin itsextended position;

FIG. 6 is a forwardly-looking sectional-view taken substantially alongthe line 6-6 of FIG. 4 and illustrates, inter alia, the trippingmechanism with the delay cycle;

FIG. 7 is a vertical sectional view taken substantially along the line 77 of FIG. 6 and illustrates the sensor, the tripping mechanism and therelationship between the tractor wheel and the cutter;

FIG. 8 is a forwardly-looking vertical sectional view takensubstantially along the line 88 of FIG. 4, the same illustrating theoperating lever assembly and the tripping mechanism;

FIG. 9 is an enlarged top sectional view taken substantially along theline 9-9 of FIG. 3 and illustrating the camming mechanism for axiallyshifting the tractor wheel; here, too, the tractor wheel is shown infull lines in its retracted position and in dot-and-dash lines in itsextended position;

'FIG. 10 is an enlarged sectional view taken substantially along theline l0-l0 of FIG. 4 and illustrates the cutting rim of the cutter incutting relationship with respect to a seaming wall of a can chime, theshoulder wheel being shown ina position engaging the outer surface of aside wall of a can to hold a can in position during and after completionof cutting and until a can is deliberately released by axial shifting ofthe tractor wheel away fromthe chime;

FIG. 11 is a forwardly looking sectional view taken substantially alongthe line llll of FIG. 4 and illustrates the position of a can as a chimeis initially inserted between the cutter and the tractor wheel while thelatter is in forwardly extending position, a chimeat this time restingagainst the tractor wheel and a first abutment to the rear of thetractor wheel, such direction being considered with respect to thedirection of rotation of the can after the cutter has commenced poweredoperation;

FIG. 12 is a sectional view similar to FIG. 11, but illustrates the canshortly after the start of a cutting operation, this figure showing thealtered angular position of a chime after the cutter has started and thecan has been swung with respect to the tractor wheel from a position inwhich a chime engages a trailing first abutment and is clear of aleading second abutment to a position in which a chime engages theleading second abutment, i.e., abutment forward of the tractor wheel inthe direction of rotation of the can, and is clear of the firstabutment, said figure also illustrating the hump raised in the top of achime as the cutter is sunk into a seaming wall and a can is swung inthe aforesaid manner;

FIG. 13 is a sectional view similar to that of FIG. 12, but illustratesthe cutter near completion of cutting when a sensor lever is beinglifted by the raised hump, such lifting initiating a delay cycle at thetermination of which the powered operation of the can opener is stoppedand the cut through a seaming wall has proceeded through a full 360 soas to complete detachment of a can top from a can body;

FIG. 14 is a schematic representation of the electrical components ofthe can opener; and

FIG. 15 is a perspective view of a can with a cut can end separated froma can body. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now indetail to the drawings, and, more particularly, to FIG. 1, there isshown an electric can opener 20 embodying this invention for removing atop end 23 of a can 22. The can 22 may be of any conventional size, asthe electric can opener'is operative with a wide range of can openerheights and diameters, thicknesses of chimes and kinds of can-formingmaterial.

The can opener includes a front housing 24 which fits together with arear housing 26 to enclose most of the operating components of the canopener. The can opener receives electrical energy from a male electricalplug 28 which is connected to a driving motor (later described) througha wire 30. The rear housing 26 supports a housing 34 for conventionalknife sharpening components, and the front housing 24 supports a cover36 for a tractor wheel 50 the location, mounting and operation of whichare subsequently detailed. As is hereinafter described, the tractorwheel is axially shiftable to squeeze a chime of a can 22 between it anda free-turning cutter 48 and is also rotatable to in turn rotate the can22 against said cutter 48 (see FIG. 10).

The top end 23 of the can 22 is affixed to the side wall of the can by aconventional double seam shown in detail in FIG. 10. The double seam, orchime, consists of an outer retroverted can hook 43 bent over from thetop edge of the side wall of the can 22 and located between an innerretroverted cover hook 44 and the seaming (outer) wall 45 of the can end23. The seaming wall 45 is engaged against the hook 43, although shownspaced from the hook 43 in FIG. 10 for more easily understanding themode of operation of the can opener 20. The seaming wall 45 is connectedby a seaming wall radius 46 (top of the chime) with a chuck (inner) wall47 which is integral with the can end 23 and which engages the innersurface of the side wall of the can.

As mentioned above, the can opener 20 has a cutter 48 (see FIGS. 2, 3,S, 7,10,11,12 and 13) which is of the form of a diabolo and the largerupper end of which has-a planar rim that constitutes a cutting edge.

The tractor wheel 50 has a frusto-conical chuck wall engaging element 51shown more particularly in FIGS. 2, 4, 5, 9, 11, I2 and 13 and acylindrical element 53 arranged to engage the top of the seaming wallradius 46 mentioned above in reference to FIG. 10. The elements 51 and53 are functionally unitary. FIGS. 3, 4, 7 and 11 show the engagement ofthe seaming radius 46 by the tractor wheel 50. The elements 51 and 53preferably have knurled can engaging surfaces to facilitate driving ofthe can seam during the cutting operation.

The tractor wheel is axially shiftable by manual operation of anoperating lever, as detailed hereinafter, be-

tween an extended position, shown in dot-and-dash lines in FIGS. 4 andS, and a retracted position, shown in solid lines in the same figures.The cutter faces the frusto-conical element 51 of the tractor wheel andin retracted position is closer to said element 51 than the thickness ofa conventional chime. In extended position the cutter is spaced furtherfrom the element 51 than the thickness of a conventional chime. As willbe seen later the element 51 is spring biassed toward the cutter topermit use of this can opener on cans having differ- ,ent thicknesses ofchime by enabling the element 51 to adjust its spacing from the cutterin retracted position.

When the chime of a can is to be cut, the tractor wheel 50 is inextended position to leave a larger-thanchime thickness space between itandthe cuttenThe whereby the initial position of the can when it isinserted in the can opener is such that the top of the can dipsforwardly and downwardly as shown in FIG. 11. Correct initialpositioning of the can between the cutter and the tractor wheel iseasily effected by an unskilled or uninstructed person due to thesimplicity of handling, viz. shifting the tractor wheel to extendedposition and pressing the top of the chime against two members, thesebeing the tractor wheel and the trailing abutment. g

The lower end of the cutter 48 is smaller than the upper cutting end andis disposed to ride on the lower edge of the seaming wall, as shown inFlG. 10, when the cutting edge has passed through the seaming wall andhas lightly penetrated the outer surface of the can hook 43 therebylimiting the depth of cut so that only the seaming wall will be cutthrough fully. For the foregoing purpose the difference in radii of theupper and lower ends of the cutter is slightly greater than thethickness of the metal used to form the cover of a conventional can. Theaxes of rotation of the tractor wheel and cutter intersect at a rightangle.

A shoulder wheel 49 which turns with the cutter 48 presses against theside wall of a can below the double seam during cutting and after a cuthas been completed and so long as the tractor wheel is in retractedposition, retains the can in the can opener. Shifting the tractor wheelto extended position releases the shoulder wheel from the can andpermits the can to be disengaged from the can opener.

The tractor wheel 50 is rotatable with a spindle 64, upon which it isfixed, when a motor 70, shown in FIGS. 2 and 14, is energized. The motor70 is energized to initiate the cutting sequence of operations byrotating the tractor wheel 50 when an operating lever 90 is manuallydepressed. FIG. 8 depicts the raised idle position of an operating lever90 in dot-and-dash lines and the lowered operative position in solidlines. The lever 90 protrudes through a slotted opening 92, shown inFIGS. 2 and 8, in the front housing 24 of the can opener 20. Theoperating lever 90 is journalled on a drive shaft 57 and is axiallymovable and rotatable with respect to the drive shaft. The drive shaft57 is integral with the spindle 64 to which the tractor wheel 50 isaffixed. The lever 90 has a raised cam 94, shown in FIGS. 4 and 9, inthe form of a pair of diametrically aligned shallow radial ribs ofcurved cross section which in the idle position of said lever enterslots 93 (FIG. 9) in the rear of a nylon disc 82. The nylon disc 82,which is fixed in a circular opening 67 in the front housing 24,supports a bushing 80 in which the drive shaft 57 is journalled. Thebushing 80, which is shown best in FIGS. 5 and 9, is stationary but thedrive shaft is axially shiftable as well as rotatable therein. FIGS. 4,5 and 9 illustrate by dot'and-dash lines the axial position of thetractor wheel 50 in its idle position and also its chime-pinchingposition by solid lines after the lever 90 is depressed.

When the lever 90 is depressed to its operative position the ribs of cam94 on the lever 90 leave the slots 93 in the nylon disc 82 to cam thedrive shaft 57 rearwardly against a pin 84 and a spring 86 so as to movethe tractor wheel 50 closer to the cutter 48. This movement alsocompresses teller springs 85 and the coil spring 86. Spring 86 normallyforces the drive shaft 57 forwardly and the tractor wheel 50 away fromthe cutter 48. The reason for utilizing the larger-than-chimethicknessspace between the wheel 50 and the cutter 48 before depressing the lever90 is twofold: first, to permit a cutting operation upon differentthickness of can chimes ordouble seams; and second to permit easyintroduction of the can chime into the space prior to the initialpenetration or cut of the cutter 48 into the outer seaming wall 45.

The coil spring 86 is a return spring that biases the tractorwheeltoward extended position when the operating lever is raised and theearns 94 are seated in the slots 93. The teller springs 85 permit thedrive shaft and tractor wheel to accommodate different thicknesses ofchime and variations in thickness of a chime along the length thereof.

A leading first abutment 96 extends forwardly from the front housing24,- said first abutment being in front of the tractor wheel in thedirection of rotation of a can being cut. As a matter of convenience anddesign both abutments 83, 96 are carried by the'nylon disc 82. Theleading first abutment 96 is desirably at about the same horizontallevel as the level of the lowermost portion of the cylindrical element53 of the tractor wheel. Thus said first abutment is spaced above thechime when the chime is initially correctly pressed against the tractorwheel element 53 and the trailing abutment 83 as shown in FIG. 11.

To initiate the cut of a chime the chime is placed between the extendedtractor wheel and the cutter, being pressed against the tractor wheelelement 53 and the trailing abutment 83 as just mentioned. When theoperating lever 90 now is depressed the drive shaft 57 and the tractorwheel will shift rearwardly to squeeze the chime between the tractorwheel 50 and the cutter 48.

This causes the cutter to sink, i.e. bite, into the seaming wall 45 ofthe double seam chime. As best seen in FIGS. 11-13 the plane of thecutting rim of the cutter is located in a fashion such that the cuttingrim tilts rearwardly and downwardly so that when the can subsequently isturned the cutter will ride down on the seaming wall and, since thecutter is stationary, the chime will rise. The inclination (dive angle)of thecutter with respect to the plane of the chime will also, when thecan starts to rotate, swing the can from the starting position of FIG.11 in which the top of the can dips downwardly and forwardly, clear ofthe leading abutment 96, to a running (cutting position) as shown inFIG. 12 wherein the top of the can engages the leading abutment and issubstantially horizontal. In such running position the top of the can isclear of the trailing abutment 83.

Thus depression of the operating lever performs a first function ofcausing the cutter to bite into the seaming wall as shown in FIG. 10.The depth of bite is limited by abutment of the lower end of the cutteragainst the lower outer surface of the seaming wall. Moreover depressionof the operating lever with consequent shifting-of the tractor. wheelelement 51 against the chuck wall 47 and aqueezing of the chime betweenthe element 51 and the cutter will bring the shoulder wheel to bearagainst the side wall of the can below the chime so that even aftercutting of the seaming wall has been completed and the tractor wheel hasstopped rotating the can will be held by the can opener until theoperating lever is raised and the tractor wheel thereby returned by thespring 86 to extended position.

The depression of the lever 90 also perfomis another function in that itinitiates, after a predetermined delay, the operation of the motor 70.When the lever 90 is depressed, the tip of a wire element 87 attached tothe lever and constituting an extension thereof slides upwardly in avertical slot 78 in a vertically movable guide 89. The guide 89, whichis shown particularly in FIGS. 2 and 8, is attached to an actuatingelement 100 of a normally open switch 102. Due to the verticalorientation of the slot 78, the initial depression or movement of thelever 90 does not close the switch 102, shown in FIGS. 2, Sand 14.However, after the lever 90 has moved the tractor wheel 50 sufficientlyfar to make the cutter 48 bite into the seaming wall 45 of the chime ofthe can 22, further downward movement of the lever I 90 raises the guide89 to close the contacts of the switch 102. As shown in FIG. 14, theswitch 102 is in series with the motor so that the motor 70 isaccordingly energized during the latter part of the movement of thelever 90.

When the motor 70 is energized, it causes, as is hereinafter describedin detail, the tractor wheel 50 to rotate and in turn to rotate the can22 in a clockwise direction as viewed from the top of the can opener 20,e.g., as seen in FIGS. 1, 4 and 9. The motor 70 has a high speed outputpinion 72, shown in FIGS. 2 and 6, that drives a gear 71 on a shaft 79.The shaft 79 is journalled in a bearing 73 mounted on the casing of themotor 70. A pinion 77 turns with the gear 71 to in turn drive anothergear 76. The gear 76 is fixed on the drive shaft 57 described above, andthe drive shaft 57 is supported by a stationary mounting plate 74 at oneend and by the bushing 80 at the other end. The drive shaft 57 and plate74 are also shown in FIGS. 4 and 5. A reduced rear end 55 of the driveshaft 57 is journalled in a socket 85a which houses the pin 84 and thespring 86, described above. When the lever 90 is depressed, the spring86 is compressed. The gear 76 is functionally integral with the shaft 57and for this purpose has splines 111, shown in FIG. 5, which are tightfits on the ends of a cross pin 1l2 in the drive shaft 57.

Reverting to the operation of the can opener, after the operating leverhas been depressed to squeeze the chime of the can between the tractorwheel and the cutter and after the tractor wheel has started to turn soas to rotate the can past the freely turning cutter in the direction ofthe arrow A, the cutter initially rides down the chime because of theinclination (dive angle) of the cutter so that the chime rises bodily;concurrently the chime and can swing to lift the front of the can (asseen in FIG. 11) and depress the rear until the top of the chime ishorizontal and the chime of the can rides against the leading abutmentto prevent further swinging of the chime. These concurrent actions ofraising and swinging the chime displace metal of the seaming wall andseaming wall radius upwardly to form a hump 120 above the start 127 of aslit 1 19 in the seaming wall formed by the cutter through the seamingwall to the hook 43. The slit 1 l9 lengthens as the can opener operates(see FIG. 12). The seamingwall radius raises in back of the tractorwheel due to the dive angle of the cutter; however the hump remainshigher than such raised radius. The hump and raised radius are clear ofthe trailing abutment 83. The chime and can rock slightly as the hump120 rides under and against the leading abutment 96, but the rocking isunnoticeable and does not affect operation of the can opener. The heightof the hump over the raised radius 46 is small but definite, a typicalsuch height being between about 0.005 to 0.020 inches. As is hereinafterdescribed, the detection of the hump 120 as it approaches the cutter(see FIG. 13) is utilized to shut off the operation of the motor 70 andthereby halt the cutting of the can 22.

As the cut 119 is made the radius 46 is raised along the length of thechime until almosta full 360 slit 119 has been formed. To shut off thecan opener 20 after completion of 360 of the slit 119, a sensor 130 isprovided which is fast on a horizontal pin 132 (see FIGS. 2, 9, 11, 12and 13) turning in a brass bushing 134. The bushing 134 is supported inthe disc 82 at the front of the housing 24. The tip of the sensor 130rests against the top edge or radius 46 of the chime and is liftedslightly when it encounters the hump 120 approaching the cutter andtractor wheel from the rear. If the detection of the hump 120 by thesensor immediately halted the motor operation, the seaming wall wouldnot have been cut a full 360 since the seaming wall would not have beenslit beneath the start of the hump and the can top 23 would remainhanging by a thread of metal below the hump. The detection or sensing ofthe hump accordingly functions to stop the motor 70 only after apredetermined delay so as to permit the cut 119 to continue for a fewdegrees up to the full 360 cutting operation and, optionally, a fewdegrees beyond.

. The sensor pin 132 is in one piece with a sensor lever 136 which isbiased by a coil spring 138 to the sensor idle position shown in fulllines in FIGS. 8 and 11. The sensor lever 136 (see particularly FIGS. 2and 8) has at the top of its upper end a notch 139. In the idle positionof the can opener 20, or while the can 22 is being cut, but before thehump is reached, the notch 139 of the lever 136 rests in a notch 144 inthe undersurface of a bar 140 (FIGS. 4 and 8) carried by a plate 142shown in FIGS. 2, 4, 5, 6 and 7. The plate 142 is journalled at its leftside as viewed in FIG. 6 on the stationary mounting plate 74. The plate142 and bar 140 are biased downwardly by a cantilever leaf spring 146(see FIG. 7) one end of which is fixed to the plate 142 and the otherend of which bears on the undersurface of the top wall of the fronthousing 24. The plate 142 normally (during the major portion of thecutting of the seaming wall) has its free end held elevated by the lever136 but as soon as the sensor 130 is lifted by the hump 120, the lever136 rotates against the spring 138 and releases, i.e., unlatches, theplate 142.

Referring to FIG. 6, when the plate 142 is unlatched, it rotatesclockwise (drops as seen in FIG. 6) a few degrees until arubber-peripheried disc 150 frictionally engages the gear 76. The freeend of the plate 142 supports the rubber-peripheried disc 150, shownalso in FIGS. 2, 4 and 7, which is rotatable on the plate 142. The disc150 is mounted on a shaft 157 journalled in the plate 142. The shaft 157extends through the plate 142 to a cam 162 which turns with the disc150. As described above, the gear 76 is part of a speed reducing geartrain from the motor to the drive shaft 57. The gear 76 is accordinglyrotating when it is engaged by the disc 150. Hence, the gear 76 causesthe disc 150, the shaft 157 and the cam 162 to rotate. As shown in FIG.6, the cam 162 has a high dwell 162A and a low dwell 162B. A torsion camreturn spring 163, shown in FIGS. 4 and 7, has one end connected to thecam 162 and the other end connected to the plate 142. The torsion spring163 functions to urge the cam 162 in a counterclockwise direction, asshown in FIG. 6, to cause a pin 181 extending from the cam 162 to engagea pin 182 extending from the plate 142. This defines the idle positionof the cam 162. As described above, the disc 150 is located above thegear 76 but normally is spaced from it.'When the disc 150 drops, itfrictionally engages the gear 76 causing the disc to rotate and in turnto rotate the cam 162 in a clockwise direction as viewed in FIG. 6. Suchrotation of the cam 162 tightens the helical spring 163 shown in FIG. 7so that when the disc 150 is thereafter lifted from the gear 76, thespring 163 restores the cam 162 to its original idle position with thepin 181 against the pin 182.

As is hereinafter described, the rotation of the cam 162 opens a switch166 in the motor circuit shown in FIG. 14 to terminate the cuttingoperation, the switch 102 still being closed during cutting since thelever is depressed. The cam 162 engages a switch follower 165 of theswitch 166 which has normally closed contacts that are closed in theidle condition of the can opener and during the cutting cycle. As thecam 162 turns in the direction of the arrow B (FIG. 6), the cam follower165 rides on the low dwell 1628 for about 135 rotation of the cam 167.Then the cam follower 165 encounters the high dwell 162A to snap openthe switch 166. By this time the chime has been driven far enough forthe cutter 48 to cut through the seaming wall under the hump. The delayprovided by the low dwell 162B of the cam 162 permits the motor 70 tocontinue operating after the sensor initiates the squence for stoppingthe cutting operation of the can 22. The cutter 48 accordingly continuesthe cut 119 for a few degrees to complete a 360 rotation of the can 22.

stops the motor 70.

After the switch 166 has operated to halt the motor 70, the chime of thecan 22 remains held by squeezing between the follower wheel and theelement 51 of the tractor wheel 50. The operating lever 90 is stilldepressed and has not as yet been raised to restore the can opener toidle condition and release the can 22. When the lever 90 is raised orrestored to its idle OFF position, it raises an extension 171 (see FIGS.2, 4 and 6) of a spring 170 having a section of tight convolutionsrotatable on a support rod 161. The support rod 161 together withanother support rod 160 attach the plate 74, as shown in FIG. 4, to thefront panel of the front housing 24. The extension 171 lies on andengages the top of the lever 90 as is shown particularly in FIGS. 4 and8, so that it is raised by the lever 90 when the lever is lifted afterthe cutting is completed and it is desired to release the can. Thespring 170 is held against axial shifting on the rod 161 by a stopcollar 189 shown in FIG. 7. The spring 170 has an offset portion 193extending under the plate 142. When the extension 171 is lifted, theoffset portion 193 lifts the plate 142, rotating it about the shaft 152and thereby lifting the disc 150 off the gear 76. With the disc 150separated from the gear 76, the spring 163 restores the cam 162 to itsidle position and recloses the switch 166.

When the plate 142 is raised, it lifts therewith the bar 140 attachedthereto above the level of the tip of the sensor lever 136. The sensorlever 136, urged by spring 138 returns the notch 139 to the notch 1'44under the bar 140 thereby to hold the plate 142 raised for the nextcutting cycle. The lever 90 is held in its raised position by a handlereturn cam 178, shown in FIGS. 6 and 8, which is forced upwardly by acantilever spring 179. The lever also is held in its raised OFF positionby cooperation between the cam ribs 94 on the lever and the slots 93 inthe back of the nylon disc 82. The return cam 178 has a tooth 199 whichengages a notch 200 in the camming surface of the lever 90. FIG. 8illustrates in solid lines the position of the return cam 178 when thelever 90 is depressed, and in dot-and-dash lines its I position relativeto the lever 90 when the lever 90 is in its normal or raised position.The tooth 199 engages a sition by the spring 138 to fit under the bar140, it rotates the sensor 130 on the other side of the disc 82 back toits normal lowered position ready for the next can. The lifting of theleveralso moves the cams 94 described above in reference to FIGS. 4 and9, back to engage the depressions 93 permitting the shaft 51 to shiftaxially back to its normal position. The spring 86, shown in FIG. 5,shifts the tractor wheel 50 to its extended position away from theinside and top of the chime of the can 20 and shifts the shoulder wheelaway from the side wall of the can. Lifting the lever 90 also permitsthe guide 89 to be lowered andopens the switch 102, this action takingplace before reclosing the switch 166.

In this manner, when the lever 90 is raised, the wheel 50is movedforward to release the can 22, and all parts are reset for the nextcutting sequence.

It thus will be seen that there is provided an electric can opener whichachieves the various objects of the invention and which is well adaptedto meet theconditions of practical use. I

As various other possible embodiments may be made of the aboveinvention, and as various changes might be made in the embodiments aboveset forth, it is to be understoodv that all matter herein described orshown in the accompanying drawing is to be interpreted as illustrativeand not in a limiting sense.

Having thus described the invention there is claimed as new and desiredto be secured by Letters Patent:

1. A method of opening a can comprising pressing a cutter into the outerside of the seaming wall of the can, rotating the can so that the cuttercuts a slit around said wall, and so that at the beginning of the slit ahump is raised at the top of the seaming wall, sensing the return ofsaid hump to its starting position and, responsive to such return,automatically stopping rotation of the can by initiating a stoppingcycle which is completed as the slit is cut fully under the hump.

1. A method of opening a can comprising pressing a cutter into the outerside of the seaming wall of the can, rotating the can so that the cuttercuts a slit around said wall, and so that at the beginning of the slit ahump is raised at the top of the seaming wall, sensing the return ofsaid hump to its starting position and, responsive to such return,automatically stopping rotation of the can by initiating a stoppingcycle which is completed as the slit is cut fully under the hump.